Using the standalone-installers 64bit on a windows 10 64bit pro machine: various 2.99 version including the latest 2.99 build #8 worked well with the project global_connections from the book QGIS Map Design written by Anita Grasser and Gretchen Peterson. After deinstalling 2.99 and installing the version 3.00 build #3 standalone the same project crashes:
This is the most annoying issue I've come up against in QGIS so far. It's reported here: https://issues.qgis.org/issues/14752 and it seems that it always surfaces in the release versions, while dev versions are fine.
Can you confirm that deactivating "Discourage labels from covering features" fixes the crash?